The invention relates to a switching device with a switching structure that includes a cage assembly having two opposite first sidewalls and one bottom wall integrally connecting the first sidewalls. The cage assembly is at least partly configured as a cage in which a slide is displaceably arranged. A moving contact bridge associated with stationary contact members is held in an opening of the slide under the pressure of a contact pressure spring. A clearance is provided between the two first sidewalls for the displacement of the contact bridge. A limit stop is provided to retain the slide.
German Publication DE 693 02 599 T2 discloses a multipole isolating switch in which an isolating structure with disconnectable contacts is provided for each pole current path. Each pole current path includes two stationary contact members and two movable contacts arranged on a moving contact bridge, which forms a pole switch with dual interruption. The moving contact bridge is acted upon by a mechanism to open and close the contacts. This is effected by a depressor, which is guided in a stationary cage. The cage is made of an insulating material and includes a bottom wall and sidewalls perpendicularly extending therefrom and is provided with windows dimensioned to allow the displacement of the contact bridge, particularly under the action of the opening and closing mechanism in case of an electrodynamic recoil. The windows further define an upper limit stop for the contact bridge. A contact pressure spring is disposed between the bottom wall of the cage and the contact bridge in a central recess of the cage, which acts as a seat and linear guide of the depressor. The depressor is thus guided along the inner surfaces of the sidewalls of the cage. The walls of the depressor have openings dimensioned to allow, on the one hand, the insertion of the contact bridge into the depressor and on the other hand, an angular movement of the bridge relative to the depressor. The cage has insulating wings which extend in longitudinal direction over a distance slightly greater than the length of the contact bridge and the height of which is sufficient to create a volume that contains the opening arcs.
This arcing chamber assembly is mounted by first inserting the depressor or slide into the cage and holding it in a defined position. This makes a window in the slide accessible from the side under the webs forming the limit stops. After the contact pressure spring has been inserted into the cage from the top through a hole in the slide, the movable switching element is inserted by means of a die into the space of the window that is still remaining after the spring has been pushed through and is then rotated by 90° into its final operating position.
A switching device of the aforementioned type is described in EP 59901859. This document discloses a switching structure 1, a contact pressure spring 2, a moving contact bridge 3 and a slide 4 in an exploded view according to FIG. 1. In the view shown, the switching structure 1 essentially consists of two parallel, elongated sidewalls 5 connected at the bottom by a bottom wall 6 (not depicted). The space 7 between the two sidewalls 5, i.e., the interior space, is accessible from all sides except from the connecting bottom wall 6. In the center and perpendicularly to the long sides 8, a guide channel 10 is formed by contours 9 in the sidewalls 5 and is provided with slots 11 in the sidewalls 5. After the contact pressure spring 2 has been inserted into this guide channel 10 and is supported against the bottom wall 6, the moving contact bridge 3 is likewise inserted into the interior from the top. The dimensions of the guide channel 10 are adapted to the slide 4. After insertion of the moving contact bridge 3, the slide 4 is inserted into the guide channel 10 such that its lateral detents 12 latch with the aforementioned slots 11 and abut the contact bridge 3. For this purpose, the slide 4 has an opening 15 configured as a recess along the underside to accommodate the contact bridge 3. The upper limit of the slots 11 serves as a limit stop 18 for the slide 4. The sidewalls 5 have external grooves 13 into which arc splitter plates 16 of an arc splitter stack 17 are inserted. Once the aforementioned components have been mounted, an assembly 1 as shown in FIG. 2 is obtained. The described switching structure 1 has lateral insulating wings, which separate an interior space of the arcing chamber in which the opening arcs are created during operation of the switching device from an exterior space of the arcing chamber in which parts of the arc splitter arrangement are accommodated.
The complete assembly 1 consisting of the switching structure and the attached arcing chamber is inserted into a bottom part 19 of the switching device as shown in FIG. 3. A top part 20 illustrated in FIG. 4, in which stationary contact members, trigger mechanisms, switching mechanisms and other components are inserted, is latched to the assembled bottom part 19.
Joining the two preassembled parts, the bottom part 19 and the top part 20, causes the contact slides 4 in the bottom part 19 and the switching mechanisms in the top part 20 to engage. A resulting problem is that when high currents are switched, e.g., in case of short circuits, an arc plasma forms which can reach the top part 20 through gaps and can cause damage there, e.g., as a result of phase flashovers from one conducting path to another, smoke and thus short circuits on a printed circuit board, etc. To prevent this, the goal is always to keep the gaps between the bottom part 19 and the top part 20 as small as possible. This results in a contradiction in the area of the contact slide 4. When the bottom part 19 and the top part 20 are joined, the contact slides 4 are guided into openings in the top part 20. Too small a gap can cause the contact slide 4 to jam if the top part 20 and the bottom part 19 are misaligned.
To solve this problem, essentially two approaches are known:    1. The openings in the top part are made correspondingly large, such that the maximum occurring misalignment between the top part and the bottom part cannot cause the contact slide to jam. This necessarily creates a large gap between the top part and the bottom part.    2. The opening in the top part is configured such that a small gap remains between the contact slide and the opening in the top part after the top part and the bottom part have been joined. The entire assembly consisting of the switching structure and the attached arcing chamber is not fixed in the bottom part. Meshing elements are formed on the top part. When the top part and bottom part are jointed, the meshing elements on the top part ensure fixation. The drawback is that the meshing elements, due to design factors, are not solid enough to withstand the loads from the arcing chamber, e.g., the mechanical loads caused by short circuiting, stresses due to vibrations or shock during transport or use, etc. As a result, the meshing elements are deformed, which in turn causes the contact slides to jam.